Brayden Schenn had a goal and two assists, Marc Gatcomb, Simon Holmstrom, Emil Heineman and Casey Cizikas also scored, and Ilya Sorokin made 17 saves for the Islanders (4-27-5), who have won three of their last four games.
The Islanders, with 89 points, moved one point ahead of the Pittsburgh Penguins for second place in the Metropolitan Division. The Penguins face the Dallas Stars at 5 p.m. ET on Saturday.
Matthew Tkachuk scored twice for the Panthers (35-34-3), who have lost six of their past seven games (1-5-1). Daniil Tarasov made 35 saves. His goals gave Florida a 2-0 lead after the first period.
“We were not 100% happy with the first period,” Islanders coach Patrick Roy said.
Tkachuk beat Sorokin on a breakaway at 8:06 to give the Panthers a 1-0 lead.
Tkachuk made it 2-0 at 14:03 of the first. Scott Mayfield and Ondrej Palat collided in the slot before Tkachuk jumped on the loose puck, going between the legs for a top-shelf finish.
“We knew before the game that Tkachuk would try to sneak behind us and make great plays. That second goal was pretty spectacular,” Roy said. “The way he brought it between his legs and put it upstairs. It was a great move by him. But after that, I mean, I felt like we just played our game, Islanders hockey. I mean, we were good on the forecheck. Our forecheck was outstanding.”